Thermionic device and circuit including the same



April 18, 1944. w BAKER 2,346,653

. THERMIONIC DEVICE AND-CIRCUIT, INCLUDING THE SAME .File d Feb. 1, 1939 1 DC PLATE AND L .scessn SUPPLY. bTI-IEI? HEATERSL- or: PLATE AND SCREEN SUPPLY 7 .J. 5 0mm hEATERsac. PLATE 4m: l SCREEN SUPPLY OTHER HEATERS m m M mv T 0 Z r 40 5 j 00 6 1'1 4 IL/ INVENTOR 65026: W BAKER BY 4m i, TT

$4M ORNEYS Patented Apr, i8, 1944 THERMIONIC DEVICE AND CIRCUIT INCLUDING THE SAME George W. Baker, New York, N. Y., assignor to Tung-Sol Lamp Works, Inc., Newark, N. J., a

corporation of Delaware Application February 1, 1939, Serial No. 253,958

14 Claims. (Cl. 250--27) This invention relates to thermionic devices and circuits including the same.

The invention has particular application to ordinary radio receiving circuits, although certain features thereof are of broader application.

One object of the invention is the elimination of the conventional pilot light shunt resistance in the heater circuit of a receiving circuit.

A further object of the invention is a novel circuit and tube wherein the resistance-temperature characteristics of the heater of the tube in the circuit is utilized for protecting a pilot light against harmful surges. To this end the pilot light which heats up much more rapidly than the heater is connected in parallel or in shunt with the heater or a portion of it which pro-' vides a low resistance shunt for the pilot light when the receiver is first turned on, thereby protecting the pilot light against high currentsurges, but as the tube heats up to normal operating temperatures provides a higher resistance shunt to give the proper operating voltages for the pilot light.

A further object of the invention is a novel and improved thermionic circuit which is characterized, among other things, by the connection of the pilot light, the anode plate of. a rectifier tube and the cathode heater so as to: cause thetion with the heater element therein to avoid harmful current surges and to give the necessary illumination while the circuit is operating.

Other objects of the invention will hereinafter appear.

For a better understanding of the invention reference maybe had to the accompanying draw ing forming a part of this application wherein:

Fig. 1 is a diagrammatic view illustrating one embodiment of the invention;

Fig. 2 is a diagrammatic view showing another modification;

Fig. 3 is a diagrammatic view showing another modification;

Fig. 4 is a diagrammatic view showing another modification;

Fig. 5 is a side view of a tube embodying the invention; and

Fig. dis a view showing the internal connections of the tube shown in Fig. 5.

Referring to Fig. 1, which illustrates the preferred modification of my invention, I have illustrated the invention as used in connection with a radio receiving circuit receiving power from the power line i. This circuit includes conventional thermionic devices or radio tubes, which are-omitted for convenience in illustration. The new and novel tube of my invention is indicated at 2 having an anode plate 3, a cathode 4 and a heating filament 5; The tube also embodies a pilot light or incandescent lamp 6, one pole of which is connected with the heater lead 5' and the other pole of which is connected with a plate lead 3. The plate 3 or its lead 3 is connected by a lead 7 with the heater 5 at a suitable point thereof so as to utilize the desired portion of the heater 5 as, for example, the portion indicated at 8, in shunt to the pilot light 6.

The section 8 of the heater 5 thereby functions as a low resistance shunt for the pilot light 6 when the receiver is first turned on and thereby protecting the pilot light or lamp against the passage of high current surges when the receiver is first connected in circuit. When the tube heats to normal operating temperature, however, the resistance value of the heater 5 and, accordingly, the shunt portion 8 increases to a point to give the proper operating voltage for the pilot light for the desired illumination. Both the pilot light filament and the heating filament are of materials which have positive temperature co-efiicients (as for example tungsten) and are so designed and proportioned that the lighting filament heats up to its normal operating temperature almost instantaneously upon closure of the circuit, while there is a substantial lag in the heating up of the heating filament. The pilot light shunt resistor and the radio tube heater or other desired portion of it are in effect one and the same. The electrical constants of the tube are so chosen that the tube operates properly with the watts dissipated in the cathode heater by the shunt portion 8 and the remainder of the heater when the pilot light islit and also operates properly with the watts dissipated in shunt portion 8 without the pilot light being lit plus watts dissipated in the 1 remainder of the heater. In this particular embodiment the watts dissipated by the shunt section 8 form only a small percentage of the total watts dissipated in the cathode heater, so that if the pilot light should burn out the operation of the tube would be substantially unimpaired. In the embodiment of Fig. 1 the current for the rectifier supplying the D. C. for the plates and screens of the circuit passes through the pilot light and the heater shunt section 8 in parallel. The conventional pilot light shunt resistance is eliminated and the circuit substantially simplified. I have shown the invention in Fig. 1 as embodied in or used with a rectifier tube 2, but it may be used with any other suitable tube in the circuit. The power line I may;

be supplied with either A. C. or D. C. The invention is of particular importance in transformless radio receivers.

In the embodiment of Fig. 2 the pilot light 8 is disposed outside of the tube Hl, but the anode plate 3 is connected, as in Fig. 1, to the heater 5 inside the tube and the pilot light 6 is connected across the heater and plate leads but on the outside of the tube as indicated, the pilot light being thereby connected in shunt with the section 8 of the heater. The proportioning of the constants and the operation of the circuit are substantially as described above in connec-..

tion with Fig. 1.

While I have shown my invention in Figs. 1 and 2 as embodied in a rectifier tube and circuit containing the same, certain features of the invention are of broader application and applicable to .tube circuits generally. In Fig. 3 I have diagrammatically shown a tube and circuit (with certain parts of the tube and heater omitted for convenience in illustration) embodying certain features of the invention wherein the tube H may be of any conventional type except that the heater 5 is provided with a tion of the receiver set if the pilot lamp should be disconnected or should burn out. In the embodiments of Figs. 1, 2 and 4 the plate current flows through the parallel circuit of which the pilot lamp 6 and the heater section are branches and this has the advantages of flexibility as to current capacities of circuits and pilot lamps, of protection against undue bumouts and of reduced disturbance in operation of the circuit.

, In Figs. 5 and 6 I have shown a tube of the embodiment shown in Fig.1. This tube embodies the conventional glass bulb 20, the stem press 2 I, support wires 22 for the electronic structure, an anode plate 23 carried by these wires 22, the cathode 4, heater 5, and heater supply leads, one of which is indicated at 5'. The cathode lead is indicated at 24, and the tube embodies conventional upper and lower mica discs lead 12 tapped to the heater 5 at any suitable point. The pilot light 6 is disposed outside of the tube H with one side of the pilot light connected exteriorly of the tube with the heater lead 5, while the other side is connected with the lead I2, the pilot light being thereby connected in shunt with the section l3 of the heater 5. The heater section l3 here functions as described above to protect the pilot light 6 against high current surges at the first closure of the circuit.

In Fig. 4 the heater 5 is tapped by a lead l2 and'the pilot light 6 is connected exteriorly of the tube i l across this lead, thus connecting the pilot light 6 in shunt with section [3 of the heater 5. The tube constructions 2 and Ill of Figs. 1 and 2 respectively are preferred over the tube Id of Fig. 4 because of the internal connection between the plate 3 and the heater and the necessity for only four tube terminals. The tube 2 of Fig. 1 is preferred over all of these because of the unitary construction of the tube and pilot light and the internal connection of the pilot light 6 across the heater section 8 as shown. The embodiment of Fig. 4 may, however, be used to advantage where provision is made for the external connections and where it is desired that the pilot lamp 6 be a separate unit and in this case the internal connection between the plate and the cathode heater is dispensed with.

The protection against undue burnoutsof the pilot lamp 6 is thus afforded in all embodiments of the invention in a particularly efiicient and simple manner-and moreover with a minimum of disturbance or interference with the opera-.

25 and 26 and centering snubbers 27, the latter being carried by the support wires 22. The pilot lightfi'may, of course, be mounted in any suitable manner, but in the embodiment shown is mounted on support wires one of which is fastened to the heater lead 5 and the other of which is fastened to a support wire 22, the latter forming the connection with the plate 23. A jumper or lead 1 connects the upper end of a wire orpost 22 with the heater at the point 28, the filament 6 being connected in parallel with the section 8 of the heater.

While I have shown the filament and heaters so designed and proportioned as to have the pilot light connected in shunt to only a small portion of the heater, certain advantages of the invention may be retained. by so 'proportiom'ng the pilot light filament and the heater as to connect the filament across a greater portion or'all of the heater, as, for example, by'designing the pilot light filament to carry a very small current as compared to the total current carried by the heater circuit.

I claim:

1. A thermionic circuit having a plurality of tube elements each having a cathode heater, which heaters are connected in series, one of said tubes having therein an illuminating filament, a plate lead and heater filament leads, said illuminating filament being interiorly connected across the plate lead and one of said heater filament leads, said plate lead being connected interiorly with said heater to connect at least a part of the heater in shunt with the illuminating filament, both said heating and illuminating filaments having positive temperature co-efiicients with the heater filament having a delayed heating characteristic with respect to the lighting filament and said heater providing a low resistance shunt for the filament when the circuit is first connected across the power line and a, higher resistance shunt across the filament when the tube is at normal operating temperatures.

2. A thermionic device of the character set forth having an anode plate, a cathode, a heating filament for the cathode plate and heater leads, and an illuminating filament contained therein and interiorly connected across the heater and the plate leads with the plate lead connected to the heater to connect at least a part ,of the heater in shunt with the illuminating filament, both said heating and illuminating filaments having positive temperature co-efilcients with the heater filaments having a delayed heating characteristic with respect to the lighting filament.

3. In a thermionic circuit having a plurality of thermionic devices with their heating elements connected in circuit and each having plate and heater leads one of said devices having its plate lead interiorly electrically connected with the heater and a pilot light connected across the plate and heater leads.

4. A thermionic device having a plate and a heater element, said plate being interiorly and electrically connected with a point on said heater element intermediate its ends and a pilot lamp connected between the plate and one end of the heater element whereby the lamp is in shunt with a part of said heater element.

5. A thermionic device having a plate and a heater element, said plate being interiorly electrically connected with said heater element at an intermediate point thereof and a pilot lamp connected between the plate and one end of the heater element whereby the lamp is shunted by a part of said heater element.

6. In a circuit of the character set forth, a thermionic device having a heater element therein and separate leads connected to each end of the heater and to an intermediate point between the ends of the heater and a pilot light exteriorly connected to one of the leads connected to one of the ends of the heater and to the lead connected to the point on the heater intermediate the ends of the heater.

7. In a circuit comprising a plurality of thermionic devices having heater elements connected in series, one of said devices having an anode plate, a cathode, a heater for said cathode, a lead for said plate and leads for each end of said heater, a pilot light connected across the plate and one of said heater leads and the plate lead being electrically connected with a point on said heater intermediate its ends to connect a portion of said heater in shunt with the pilot light.

8. In a thermionic device of the character set forth, a heating filament and a lighting filament, said lighting filament being connected across a part only of the heating filament so as to permit the device to operate at substantially normal efficiency when the lighting filament is broken, said filaments being so proportioned and designed with respect to each other and to their connections that the heating filament heats up to its normal operating temperature only an appreciable time after the lighting filament heats up to its normal operating temperature.

9. In a circuit comprising a plurality of thermionic devices having heater elements connected in series, one of said devices having an anode plate, a cathode, a heater for said cathode, a lead for said plate and leads for each end of said heater, a pilot light connected across the plate and one of said heater leads and theplate lead being electrically connected with a point on said heater intermediate its ends to connect a portion of said heater in shunt with the pilot light, including a separate lead interiorly tapped to said point of the heater intermediate its ends, said plate lead being connected exteriorly of the thermionic device with said tapped lead to provide the electrical connection between the plate and said point, and said pilot light being exteriorly connected across said tapped lead and said one of said heater leads.

10. In a radio set having tubes including a rectifier tube, said tubes having heaters, a circuit in which said several heaters are connected in series across a source of power, and a dial light connected in shunt across at least a portion of the heater of said rectifier tube, said rectifier tube having a plate and a cathode, connections from said cathode for supplying plate current voltage to the others of said tubes, and a return connection from the plate of said rectifier tube to said first mentioned circuit, said connection being such as to cause the plate current of said rectifier tube to pass in part at least through said dial light.

11. In a radio set having vacuum tubes with heaters, a circuit in which said heaters are connected in series across a source of power, a dial light connected across a portion only of one of said heaters, said heater having a longer thermal lag than the heaters of the remainder of said tubes in said radio set.

12. A thermionic device having an anode plate and a heater element, said heater having a tap intermediate the ends thereof and separate leads from an end of said heater, said tap and said anode plate respectively for exteriorly connecting said anode plate with said tap and a pilot lamp in shunt with a portion of said heater whereby the plate current of the device is caused to pass in part at least through said pilot lamp and the shunted portion of the heater protects the pilot lamp against surges at starting.

13. In a circuit comprising a plurality of thermionic devices having heater elements connected in series, one of said devices having an anode plate, a cathode, a heater for said cathode, a lead for said plate and leads for the ends of said heater, a pilot light exteriorly connected across the plate and one of said heater leads and the plate lead being interiorly electrically connected with a point on said heater intermediate its ends to connect a portion of said heater in shunt with the pilot light.

14. A thermionic device having an anode plate and a cathode heater element, said anode plate being interiorly electrically connected with said heater element at an intermediate point thereof and separate leads for said anode plate and an end of said heater element for exteriorly connecting a pilot lamp between the plate and one end of the heater element, whereby the lamp is shunted by portion of the heater element and the plate current fiows through the parallel circuit of which the pilot lamp and said portion of the heater element form branches.

GEORGE W. BAKER. 

